Distribution and characteristics of world climate

I. Global climate zones and climate types

Global climate is formed under the comprehensive influence of solar radiation, atmospheric circulation, underlying surface properties and human activities. According to the differences in the basic characteristics and causes of climate in different parts of the world, the global climate can be divided into several climatic zones. In the same climate zone, on the one hand, the climate has some similarities; On the other hand, the climate is different because of the different land and sea positions, distance from the sea, ocean current properties, topography and local circulation conditions. Accordingly, some climatic zones can be divided into several climatic types. For example, in tropical, subtropical and temperate zones, the three climatic types can generally be divided into east coast, inland and west coast.

Distribution characteristics of climatic zones in the world

The key to the division of climate zone and climate type is to determine the boundary between climate zone and climate type. But there is no recognized standard in academic circles so far. This is because all climate zones and climate types in nature are gradual, and there is no obvious dividing line. As for the dividing line on the distribution map of climate types, it is artificially divided and is actually a transitional zone with a certain width. At present, the division of climate zone is usually based on isotherm, and the division of climate types in climate zone usually considers the influence of precipitation and topography.

In climatology, isotherms are usually used as the boundary to divide climatic zones. Average temperature in the hottest month 10? Taking the isotherm as the dividing line between the cold zone and the temperate zone, the maximum Leng Yue temperature is 18? Isotherm is the dividing line between temperate zone and tropical zone. Temperate zone spans the widest latitude, and the temperature difference between high and low latitudes is large. It is customary to further divide sub-frigid zone and subtropical zone in temperate zone. The former is the transition zone from temperate zone to cold zone, and the latter is the transition zone of tropical zone. In each climate zone, according to the unbalanced distribution of climate factors such as temperature and precipitation in space and time, various climate types are further divided. It can be seen from the world climate distribution map that although the arrangement and combination of climate types on various continents are complex and diverse, the imprint of zonality law is still clearly visible. From the equator to the polar regions, all kinds of climate types are basically replaced by latitude.

The zonality of climate is particularly obvious in the low and high latitudes of the mainland, because the contradiction between cold and warm is relatively stable and constant in these two latitudes. The former receives more sunlight and heat from the sun, and warm air is the main contradiction, with high temperature all year round and long summer without winter; The latter accepts less sunlight and heat, and cold air is the main contradiction. The temperature is low all year round, and winter is long without summer. Therefore, in low-latitude and high-latitude areas, various climate types alternate from north to south according to latitude, mostly distributed in strips, and some even cross the continent from east to west. Such as equatorial rainy climate, tropical dry and wet season climate, low latitude tropical arid and semi-arid climate, polar ice sheet climate, polar long cold climate, high latitude sub-frigid continental climate, etc., are all climate types with obvious zonality.

There are many kinds of climate classification, each with its own advantages and disadvantages. On the basis of Schaller's dynamic climate classification, China climatologists modified it appropriately, and divided the global climate into three latitude zones and plateau climate, and divided it into several climate types in each latitude zone.

(A) land low latitude climate

The low latitude climate is mainly controlled by equatorial air mass and tropical air mass, with high temperature all year round, and the monthly average minimum temperature is above 15℃. The main circulation systems affecting climate are intertropical convergence zone, trade winds, equatorial westerly winds, tropical cyclones and subtropical high. The seasonal movement of these systems leads to the seasonal variation of precipitation.

The low latitude climatic zones on land include equatorial zone and tropical zone. It consists of five climate types: equatorial rainy climate, tropical marine climate, tropical monsoon climate, tropical dry and wet season climate and tropical drought and semi-drought. Except for the tropical arid and semi-arid climate, which is distributed inside and outside 30 degrees north and south latitude, other climate types all appear within 25 degrees north and south latitude. Specifically, the land low latitude climate zone includes:

1. Equatorial rainy climate

Also known as the tropical rain forest climate, it is mainly distributed in the range of 5-10 north latitude on both sides of the equator, including the Amazon Plain in South America, the Congo Basin in Africa, the Gulf of Guinea and most parts of the Malay Archipelago in Asia. Located in the low latitude, the source of equatorial air mass, and at the same time in the equatorial low pressure area, the trade winds in the northern and southern hemispheres meet and rise here, and there is more convective rainfall. In summer, the average temperature of each month is 25-28℃, and the daily range is slightly larger than that of annual range. The average annual precipitation is more than 2000 mm, and the minimum monthly precipitation is more than 60 mm. The zonal soil is tropical rain forest latosol.

2. Tropical dry and wet season climate

Also known as the savanna climate, it is mainly distributed in the periphery of the equatorial rainy climate zone, which can generally reach about north-south latitude15 or 25. Including Sudan grassland in Africa, Ethiopian plateau, northern East African plateau and South African plateau, Brazil plateau and Orinoco River plain in South America, Pacific coast in Central America and northern Australia. The climate is characterized by high temperature all year round and obvious dry and wet seasons. In the dry season, controlled by the trade winds, tropical continental air masses prevail, with little rain; The rainy season is controlled by the equatorial low pressure area, and it is wet and rainy when the equatorial airflow convergence zone moves. The vegetation soil type is tropical savanna red brown soil.

3. Tropical arid and semi-arid climate

It is mainly distributed in the inland and west on both sides of the Tropic of Cancer, roughly between the north and south latitudes 15-30. Typical tropical arid climate zones include Sahara Desert in Africa, kalahari desert and namib desert, Arabian Desert in West Asia, thar desert in South Asia, desert in central and western Australia and Atacama Desert on the west coast of South America. Controlled by subtropical high and trade winds all the year round, tropical continental air masses prevail and the climate is dry and hot. For example, the "hot pole" and "dry pole" in the world all appear in this type of area. Berbera, in the northern part of the Somali Peninsula in Africa, once recorded an extreme maximum temperature of 63℃ and became the "hot pole" in the world. The average annual rainfall in Atacama Desert in northern Chile of South America is close to 0 (0.7mm measured in Allica), and it never rains during the period from 1845 to 1936, which is called the "dry pole" in the world. As for the tropical semi-arid climate, it is distributed at the outer edge of the arid climate zone and transits to the tropical dry and wet season climate zone and the subtropical summer arid climate zone respectively. Vegetation soil type is tropical desert (or desert grassland) desert soil.

4. Tropical monsoon climate

Mainly distributed in Indochina Peninsula, Indian Peninsula and Philippine Islands in Asia. In the season when the solar altitude angle is large, the equatorial trough extends northward to about 30 north latitude, and with the influence of land and sea thermal factors, a thermal depression is formed in the northwest of the South Asian subcontinent. At this time, the southwest monsoon blowing from the Indian Ocean, that is, the summer monsoon, prevailed, and the rainy season was formed due to heavy precipitation. In the season when the solar altitude angle is small, the equatorial trough moves southward, and coupled with the thermal difference between land and sea, a weak high pressure develops in the northwest of the subcontinent. At this time, the northeast monsoon, that is, the winter monsoon, prevailed, and the thousand seasons were distinct due to the lack of precipitation. In addition, some areas can be subdivided into cool season and hot season. The climate in this area is long in summer without winter, the annual average temperature is above 20℃, and the annual average precipitation is generally 1 500-2 000 mm, or even more.

5. Tropical maritime climate

It is mainly distributed in the east coast of the mainland and several islands in the tropical ocean in the north latitude10-25 trade wind zone, including the east coast of Central America and the West Indies, the narrow strip of the east coast of Brazil Plateau in South America, the east of Madagascar Island in Africa, the coast of Queensland, Australia, and the Hawaiian Islands in the Pacific Ocean. These areas are located on the windward coast of the trade winds, and tropical marine air masses prevail all the year round. In addition, after landing, the trade winds in coastal mountains rose, so a high-temperature and rainy climate with marine characteristics was formed. The type of vegetation soil formed here is the same as that of equatorial rainy climate, and it is tropical rain forest latosol.

(2) land mid-latitude climate

The mid-latitude zone is the intersection of tropical air mass and polar air mass. The main circulation systems that affect climate are polar front, prevailing westerly wind, extratropical cyclone and anticyclone, subtropical high and tropical cyclone. The weather changes aperiodically and the precipitation changes seasonally. The land mid-latitude climate zone is a region where cold and warm air currents compete with each other, and the seasonal and aperiodic changes of temperature and precipitation are remarkable. According to the heat condition, the mid-latitude climate zone on land can be divided into temperate zone and subtropical zone. Because the global continent is most seriously divided by the ocean in the mid-latitude region, there are often different climatic phenomena and characteristics on the east and west sides of the continent and within the continent, which show as dry and wet zones, thus affecting the regional differentiation of the natural environment.

1. Land temperate climate

The land temperate zone is mainly distributed in the region of 35 ~ 60 N, and the temperate zone in the southern hemisphere is not large, because only a small piece of land extends to the south of 40 N. Due to the influence of ocean division, the temperate zone has obvious east-west differentiation. Generally, the east coast of the mainland has a temperate continental humid climate or temperate monsoon climate, the west coast of the mainland has a temperate maritime climate, and the inland between them has a temperate continental arid and semi-arid climate.

(1) temperate continental humid climate

It is mainly distributed in the eastern part of North America and the eastern part of Eurasia temperate maritime climate zone between 35 and 55 north latitude, that is, the eastern part of Eurasia temperate maritime climate zone and the area about 40 to 60 N east of North America100 W. The temperature and precipitation of this climate are somewhat similar to those of temperate monsoon climate, but the seasonal changes of wind direction and wind force are not as obvious as those of temperate monsoon climate. From the cause of formation, its cold and dry winter is not caused by the continental monsoon, but by the deep westerly wind blowing from the ocean, which has undergone continental degeneration, so the temperature is low and the precipitation is less; There is convective rain in summer, but the concentration of summer rain is not as significant as that of temperate monsoon climate.

(2) temperate maritime climate

It is mainly distributed in the western part of the mainland at 40-60 north latitude, including the western and southern Scandinavia in Europe, most parts of central and western Europe, the Pacific coast west of cordilleras in North America and Canada, the western Andes in southern Chile in South America, and Tasmania and New Zealand in Australia. The westerlies and temperate marine air masses prevail here all the year round, and warm currents pass along the coast, forming a climate characteristic of warm in winter and cool in summer, small annual variation, more precipitation throughout the year and a little more rainfall in autumn and winter. Besides, it's rainy, cloudy and sunny here.

(3) temperate monsoon climate

It is mainly distributed in East Asia near 35-55 N, including the north of Qinling-Huaihe Line in eastern China, the Korean Peninsula, northern Japan and southern Russian Far East. The climate is similar to the subtropical monsoon climate. Winter is controlled by temperate continental air mass, which is cold and dry with large temperature difference between north and south; In summer, it is warm, hot and rainy, and the temperature difference between north and south is small due to the influence of temperate marine air mass or denatured tropical marine air mass. In addition, the four distinct seasons and significant weather non-periodic changes are also the main characteristics of temperate monsoon climate. Because the climate characteristics of the above temperate climate types are mainly humid (semi-humid in North China Plain and Northeast China Plain), temperate broad-leaved forest landscape (forest and grassland landscape in North China Plain and Northeast China Plain) is generally developed, but there are some differences. There are more kinds of broad-leaved trees in East Asia than in Europe, including Quercus mongolica, Quercus liaotungensis, Acer, Tilia lindleyana, Birch and other miscellaneous trees. In western Europe, pure forests composed of single tree species are often formed, such as beech forests and oak forests. The broad-leaved forest landscape in North America (including the southern Great Lakes, Appalachian Mountains, Mississippi River Basin and Atlantic coastal lowlands) is dominated by American beech and sugar maple. Colored brown soil and gray brown soil are mainly developed in the whole temperate moist broad-leaved forest belt, while cinnamon soil and black soil are mainly developed in semi-humid forest grassland belt.

(4) temperate continental arid and semi-arid climate

Also known as temperate desert and temperate grassland climate, it is mainly distributed in the hinterland of Asia and North America, Patagonia Plateau and pampas grassland in South America. This climate zone in Asia and North America is far away from the sea, deep inland, surrounded by mountains and plateaus, and it is difficult for humid ocean air to reach. Temperate continental air masses prevail all the year round, forming a temperate continental arid and semi-arid climate with hot summer and little rain in winter. Generally speaking, the average annual precipitation in arid climate is below 250 mm, and the average annual precipitation in semi-arid climate is 250-500 mm. This climate zone in South America is located on the east coast of the continental westerly belt, which is a rain shadow zone, and there are tall Andes mountains on the west coast. The west wind sinks after crossing the mountain, which is warm, dry and rainy, and there is a cold current along the coast, so the air is stable and precipitation is scarce. The vegetation in temperate continental arid climate is sparse, and the vegetation land type is temperate desert soil; The vegetation soil type in temperate continental semi-arid climate zone is temperate grassland chestnut soil.

2. Terrestrial subtropical climate

Terrestrial subtropics are mainly distributed in areas between 25 degrees and 40 degrees north and south latitude. Due to the subtropical high and the location of land and sea, the east coast of the mainland generally has a subtropical humid climate or a subtropical monsoon climate; The west coast of the mainland has a subtropical summer dry climate (Mediterranean climate); There is a subtropical continental arid and semi-arid climate between them.

(1) subtropical humid climate

It is mainly distributed in the 25°-35° N zone in the east of North America, the southeast edge of Brazil Plateau in South America, the east of the middle and lower reaches of parana river, and the east of pampas Grassland. In addition, it is also distributed in the southeast coast of Africa and the southeast coast of Australia, but the area is small. Its main feature is that the temperature difference between winter and summer is smaller than that in subtropical monsoon climate zone, and the precipitation distribution in one year is even than that in monsoon climate zone. These areas are similar to the East Asian subtropical monsoon climate zone (the east coast of the mainland) in latitude and land and sea position, but because the mainland area and adjacent ocean area are small, the thermal difference between land and sea is not as prominent as the latter, so a typical monsoon climate has not formed.

(2) Subtropical monsoon climate

It is distributed in subtropical East Asia, mainly including the area south of Qinling-Huaihe River in eastern China, the area north of tropical monsoon climate zone, southern Japan and the southern tip of Korean Peninsula. The change of air pressure configuration caused by different sea-land temperatures in winter and summer is the main reason for the climate in this area. In winter, the Asian continent is controlled by the high pressure, and the northwest wind blows from the land to the ocean, that is, the winter wind, with less precipitation; In summer, the Asian continent is controlled by low pressure, from the southeast wind blowing from the ocean to the land, that is, the summer monsoon, with more precipitation.

Evergreen broad-leaved forest is the main vegetation in subtropical humid climate and monsoon climate, and the corresponding soil types are red soil and yellow soil.

(3) subtropical dry summer climate

Also known as the Mediterranean climate, it is mainly distributed on the west coast of the mainland at 30-40 degrees north and south latitude. The Mediterranean region has the largest summer drought climate range and the most obvious characteristics. In addition, it also includes the Pacific coast of the southwestern United States, central Chile, the southern tip of Africa and the southern tip of Australia. The planetary wind system on the west coast of subtropical continent is normally distributed, and the climate here is controlled by the seasonal alternation of subtropical high and westerly winds. In summer, this area is controlled by subtropical high pressure zone, dominated by downdraft, and the climate is dry and hot; Winter is controlled by westerlies, where temperate ocean air masses prevail, cyclones are active and precipitation is high. Therefore, hot and dry summer and mild and rainy winter are the main features of the Mediterranean climate. This type of climate zone mainly forms evergreen broad-leaved forest belt, mainly evergreen shrub forest and brown soil.

(4) subtropical continental arid and semi-arid climate

It is mainly distributed in the subtropical continent, including the Iranian Plateau and Anatolia Plateau in West Asia, the inland plateau in the western United States and Granchako in South America. The arid climate is formed because the inland is far away from the sea or blocked by mountains, and the humid ocean airflow is difficult to reach, and it is located in the subtropical zone, so it is hot in summer and mild in winter. Semi-arid climate belongs to the type of transition from arid climate to other climate. The vegetation here belongs to desert grassland, usually xerophytes and gramineous plants, and the soil belongs to semi-desert light brown soil.

(3) Land high latitude climate

The land high latitude climate zone mainly includes the sub-frigid zone north of 50' north latitude in the northern hemisphere, the land frigid zone in the Arctic Circle and the Antarctic continent in the southern hemisphere. Arctic Ocean and Antarctic ice sheet are the sources of glacial air mass and Antarctic air mass respectively, while Siberia and Canada are the sources of polar continental air mass in Asia and North America respectively. On the ice front where the ice air mass meets the polar air mass, a cyclone moves from west to east. The temperature here is low, including the world cold pole and the northern hemisphere cold pole. The main climate types are sub-frigid continental climate, polar long cold climate and polar ice sheet climate. The characteristics of several climatic zones are:

1. Subrigid continental climate

Also known as the sub-cold zone coniferous forest climate, it is generally distributed between 50 and 70 north latitude, and the west coast of the mainland is between 60 and 70 north latitude, including most of North Asia, Northern Europe, Alaska in North America and central and northern Canada. The climate here is mainly influenced by the polar ocean air mass and the polar continental air mass, and it is the source of the polar continental air mass. In winter, there are many opportunities for ice air masses to invade; In warm seasons, tropical continental air masses can also penetrate. The climate is characterized by strong continental nature, long and cold winter, short warm season, high annual temperature difference, little precipitation, concentrated warm season and weak evaporation, belonging to a cold and humid environment. Vilho Yansk and Oymyakon in the northeast of Siberia, with an average temperature of -50℃ in June+10/October in 5438 and an absolute minimum temperature of -73℃, are cold poles in the northern hemisphere. The absolute annual temperature difference of Vilho Jansk reaches 65,438+0,065,438+0.8℃, which is the highest annual temperature difference.

2. Long-term cold climate in polar regions

Also known as tundra climate, it is mainly distributed on the coasts and islands of the Arctic Ocean in Eurasia and North America, and the latitude is roughly between 70 and 75 N, which is already within the Arctic Circle, so the extreme phenomenon of day and night is obvious. The climate is characterized by winter all year round, with the monthly average temperature of 0-IO ~ C for only 65,438+0-4 months in a year, and the precipitation is scarce, which mostly belongs to the glacier front, mostly snow, with plenty of clouds and weak evaporation.

3. Polar ice sheet climate

Mainly distributed in the Antarctic continent, the Arctic Ocean and most parts of Greenland. The latitude is the highest here, and the longest day and night can last for half a year. Controlled by polar high pressure for many years, it is the source of ice ocean air mass and Antarctic air mass. It is very cold all year round, with little precipitation, and snowstorms are common. Due to years of accumulation, a huge ice sheet has been formed. The Antarctic region is the world's cold pole, wind pole and the driest ice continent, while the Arctic region is a sea of ice sheets and floating ice.

(4) Plateau climate

Mainly distributed in the Himalayas, Pamirs and Qinghai-Tibet Plateau in Asia, Cordillera Mountains in North and South America, Alps in Europe and Kilimanjaro in Africa. Because the climatic factors such as temperature and precipitation change vertically with the altitude of the terrain, a vertical climate zone structure is formed. Different mountains or plateaus have different vertical climate zone structures, that is, the same mountain or plateau often has different vertical climate zone structures due to the differences in internal slope direction, height and position.

Second, the distribution law of the world climate

Climate, like all natural phenomena, is not chaotic in its distribution and change, but has differences and similarities, showing certain regularity. On the basis of comprehensive consideration of the factors that form climate, by analyzing the basic contradictions that constitute climate differences, namely, cold and warm contradictions, dry and wet contradictions, high and low pressure contradictions, and combining with the relationship with natural landscapes, we can simplify and summarize the complex world climate and divide several climate types. Latitude and land and sea are the same, so the regions in the same position in the global atmospheric circulation often belong to the same climate type, and the specific boundaries between climate types are subject to terrain and other factors. The so-called world climate distribution law is directly reflected in the arrangement and combination of various climate types. The dominant factor of climate formation, that is, the thermal difference caused by the uneven distribution of solar light and heat on the earth's surface, and the resulting global pressure belt, wind belt and its seasonal displacement, lead to the general trend of climate types changing according to latitude, which is the basic law of world climate distribution-zonality. On the other hand, land and sea distribution, ocean currents, topography and other factors have destroyed the zonality of climate to varying degrees, resulting in differences between the west coast, inland and east coast in the same latitude zone, as well as differences caused by different topographic conditions, which is the non-zonality of world climate distribution. There are both connections and differences between them, and the distribution of a world climate pattern is the product of their unity of opposites.

(A), the zonality of climate

According to the amount of sunlight and heat obtained, the earth's surface is divided into five basic climatic zones: tropical zone, south temperate zone and north temperate zone, south frigid zone and north frigid zone.

On both sides of the equator on all continents, it extends about 5- 10 from south to north, such as Amazon Plain in South America, Congo Basin in Africa and some islands in Southeast Asia. It belongs to the equatorial rainy climate (also known as the equatorial rainforest climate), characterized by high temperature and rain all year round, no seasonal change, and the average monthly temperature is 25-28? The daily range is slightly larger than that of annual range; The annual precipitation is more than 2000 mm, and the minimum rainy month precipitation is also more than 60 mm, with many thunderstorms. The hot and humid climate is very conducive to plant growth, with diverse tree species, strong layering and evergreen seasons.

Both sides of the equatorial rainy climate zone, roughly south of north latitude15, belong to the tropical dry and wet season climate (also known as savanna climate), which is widely distributed in Africa, South America and Australia. The formation of this climate type is closely related to the seasonal displacement of pressure zone and wind zone.

Take the northern hemisphere as an example. In winter, the sun shines directly in the southern hemisphere, located in the northeast trade wind area, where tropical continental air masses prevail and the climate is dry. In summer, the sun shines directly in the northern hemisphere, and the trade winds also move northward. Under the control of equatorial low pressure, southwest wind blows from equatorial sea surface, and precipitation increases obviously. Therefore, the climate is obviously divided into dry and warm seasons, and the annual precipitation is about1000 mm; This zone still has the characteristics of high temperature in the low latitude zone, but the temperature in the year is slightly higher than that in the equator.

A rainy climate. Due to the limitation of water conditions, trees are gradually sparse, forming a savanna landscape, which is gradually replaced by grassland with the increase of latitude. In the wet season, tall grass and shrubs with dense growth and sparse trees grow everywhere; When the dry season comes, the soil cracks, the grass turns yellow and the trees fall.

Outside the tropical dry and wet season climate zone, it reaches the west coast of the mainland on both sides of the Tropic of Cancer, with an average position of 15-30, which belongs to the tropical arid and semi-arid climate (also known as tropical desert climate) and is most widely distributed in northern Africa, southwestern Asia and central and western Australia. The distribution area of tropical arid climate is controlled by subtropical high and trade winds all the year round. The tropical continental air mass prevails and the airflow sinks. The main feature of the climate is dry heat. The temperature is quite high, and the world's "hot pole" has appeared in this climate type area (the absolute highest temperature in Azizia, Libya is 58), but it is hot during the day and cool at night, and the daily temperature difference is particularly large. Extreme precipitation

Rare, less than 200 mm a year, and the variability is great, even it doesn't rain for many years, and the precipitation in a year is often concentrated in several sudden rainstorms; Wan Li has no clouds in Wan Li all the year round, with strong sunshine and strong evaporation, which further aggravates the dryness of the climate. The main feature of tropical semi-arid climate is that the rainy season is short, and the annual precipitation can be increased to 500 mm, which is distributed at the outer edge of tropical arid climate zone and transits to tropical dry and wet season climate zone and subtropical summer arid climate zone respectively. The former short rainy season appears in summer, and its causes are similar to those in tropical dry and wet seasons; The latter's short rainy season occurs in winter, the temperature is not as high as the former, similar to subtropical summer, and the climate is dry.

In the polar regions and their vicinity, including Greenland, the Arctic Islands and the Antarctic continent, it has a polar ice sheet climate. The whole winter is in a state of long night. Although it is a perpetual day in summer, the sun shines obliquely and the heat gained is weak, so the temperature is below freezing point all the year round. The absolute minimum temperature of -94.5 was observed near the South Pole, which is the "cold pole" in the world. The ground is covered with thick ice and there are many cold storms, which make it difficult for plants to grow.

There is a polar permafrost climate zone (also called tundra climate) in the south of the ice sheet climate and the northern edge of Eurasia and North America. It is characterized by long and cold winters and short and cool summers. The monthly average temperature is only above freezing point for 2-3 months in a year, but it does not exceed 10. The annual precipitation is about 200-300mm, mainly snow, and the ground is permafrost. Only low-level plants such as lichens and mosses can grow.

Next to the polar long cold climate zone is the sub-frigid continental climate zone (also known as the sub-frigid coniferous forest climate), which spans the Eurasian continent and the North American continent between 50 and 70 N. The winter here is still long and cold, but the summer is quite warm. The monthly average temperature is above 10, and the highest temperature can reach 18-20, especially in annual range. The annual precipitation increases to 300-600 mm, mostly summer rain, and the relative humidity is very high due to weak evaporation. In this climate, conifers such as pine, cypress and Chinese fir are suitable for growth.

Compared with other continents in the world, Africa has a simple outline and no ups and downs on the ground, and is mainly located in low latitudes, so it reflects the zonality of climate, and the climate types are replaced by latitudes, and the arrangement is almost symmetrical. Eurasia and northern North America are located in high latitudes, with vast land and obvious climatic zonality. The climate types change from north to south in turn, especially the polar long cold climate and the continental climate in the sub-cold zone are distributed in strips, spanning the east and west sides of the mainland.

Second, the non-zonality of climate.

The distribution of land and sea and the seasonal changes of air temperature, air pressure, wind direction and precipitation on land and sea have caused the basic differences between marine climate and continental climate, especially in mid-latitude areas, three different types of climate can be clearly distinguished in the same climate zone: west coast, inland and east coast. The main characteristics of maritime climate are: warm in winter and cool in summer; the temperature in autumn is higher than that in spring; the annual range and diurnal range of temperature is small; the most and hottest months in Leng Yue appear later in a year (for example, Leng Yue in the temperate zone of the northern hemisphere is in February at most and the hottest month is in August); The humidity is high, there are many clouds, the precipitation is abundant, the seasonal distribution is even, and there is much rain in winter. The main features of continental climate are roughly opposite to those of maritime climate: Leng Xia is hot in winter, the temperature in spring is higher than that in autumn, the daily temperature range is greater than that in annual range, and the most Leng Yue and hottest month appear earlier in a year (for example, the most Leng Yue in the temperate zone of the northern hemisphere is in 65438+ 10 month, and the hottest month is in July); Low humidity, less clouds, less precipitation, concentrated in summer. The distribution of marine climate and continental climate in all continents of the world also presents certain laws. Generally speaking, all areas affected by marine air masses have maritime climate characteristics; All areas affected by continental air masses have continental climate characteristics. Therefore, from the ocean to the inland, the maritime nature of the climate is gradually weakened, while the continental nature is gradually enhanced. But the actual situation is more complicated, especially in the coastal climate difference. The east coast and west coast of the mainland are close to the ocean, but the climate is completely different, some are continental climate, some are maritime climate, and some are the mixture or transition of maritime climate and continental climate. This is mainly determined by the direction and back of the sea breeze caused by atmospheric circulation, and the nature and topographic factors of coastal currents also have great influence. Secondly, as far as latitude zone is concerned, as mentioned above, in low latitude and high latitude areas, especially in the equatorial rainy climate, polar long cold climate and polar ice sheet climate distribution range, the contradiction between cold and warm is in a relatively stable and constant state, so the contrast between maritime climate and continental climate is not obvious, and the climate difference between east and west coasts is not great. In mid-latitude areas, cold and warm air is often in a state of struggle and transformation. The seasonal and aperiodic changes of temperature and precipitation are very obvious, and the land area is particularly vast (northern hemisphere), so the contrast between marine climate and continental climate is remarkable, especially the continental climate, and the difference between the east and west coasts of the mainland is remarkable. On the west coast of Eurasia, the area above 40 north latitude is in the westerly belt all the year round, which is deeply influenced by the ocean air mass. There is a warm current along the coast, no cold in winter and no heat in summer. The average temperature in Leng Yue is above 0, the hottest month is below 22, and the daily temperature difference is small throughout the year. There is precipitation all year round, especially in autumn and winter. The annual precipitation is above 1000mm, and it can reach above 2000-3000mm on the windward side of the mountain. This is a typical temperate maritime climate. Plants grow luxuriantly here, trees are closed, and they are spread all over broad-leaved forests or mixed coniferous and broad-leaved forests. In the region of 40-30 N, due to the seasonal displacement of subtropical high, it is in the westerly belt in winter, and the polar ocean air mass prevails, which is mild and humid; In summer, controlled by subtropical high and northeast trade winds, tropical continental air masses prevail and are dry and hot; The annual precipitation is about 750mm, and more than 70% is concentrated in winter. This is a subtropical dry summer climate (also known as Mediterranean climate), with maritime climate characteristics in winter and continental climate characteristics in summer, and the corresponding vegetation types are evergreen trees with hard leaves and various shrubs. The area south of 30 N is in the trade wind area all the year round. The northeast wind blows from the mainland to the sea, and the climate is extremely dry, and the desert reaches the sea directly. This is a coastal tropical arid climate, which is different from the inland tropical arid climate at the same latitude. Because the cold current passes along the coast, it is not so hot in summer, with a small annual range, many foggy days and high relative humidity, which is sometimes called tropical foggy desert climate. The above climate types are distributed in the corresponding latitudes on the west coast of the earth's continents, changing in the order of temperate maritime climate-subtropical summer dry climate-tropical dry climate, connecting with the continental climate of the sub-cold zone at high latitudes and connecting with the tropical dry and wet season climate at low latitudes. However, due to the influence of topography, their distribution range is very different. For example, in the western part of the American continent, the huge Cordillera-Andes mountain system runs through the north and south, which makes the climate types on the west coast of the continent distributed in a narrow zone with limited scope. In the west of Eurasia, the terrain is flat, the coast is tortuous, the sea breeze can go deep inland, and there are Mediterranean waters, so the temperate maritime climate and subtropical summer dry climate on the west coast are widely distributed. There is no huge terrain barrier in North Africa and Western Australia, and the tropical arid climate on the west coast is integrated with the inland tropical arid climate. On the east coast of Eurasia, the distribution of Xia Feng direction and ocean current in winter is obviously compared with the west coast at the same latitude, so the temperature, precipitation and their seasonal distribution are completely different. In the area north of latitude 40, in winter, due to the existence of continental high, northwest and north winds blow, polar continental air masses prevail, and cold currents pass along the coast, so it is cold and dry, and the climate is continental; In summer, the high temperature and low air pressure on the mainland can attract the southeast wind to land, resulting in more precipitation. This shows that the eastern part of the mainland is very different from the western part of the temperate zone with the same latitude. The seasonal changes of wind direction, temperature and precipitation in 40-30 N region are similar to those in the western region with the same latitude, but due to the subtropical latitude, the temperature rises and the precipitation increases. The climate features are mainly cool and dry in winter and humid and hot in summer, which is obviously different from the western region at the same latitude. The area south of 30 N is located on the east bank of the trade wind belt, which welcomes the sea breeze all the year round, and there is warm current passing along the coast, so the temperature is high, the precipitation is abundant, and the seasonal distribution is relatively uniform, but there is more rain in summer, which has the characteristics of low latitude maritime climate, which is just the opposite of the tropical arid climate on the west bank of the same latitude.

Because the area of each continent is wide and narrow, the influence of land and ocean factors on the climate of the east coast of the continent is different. The eastern part of Eurasia lies between the largest continent and the largest ocean in the world, and the thermal difference between land and sea is particularly great. Under the control of seasonal high and low pressure, the wind direction, wind force, temperature and precipitation in Xia Feng change significantly in winter, forming a special monsoon.